1. Field of the Invention
The present invention relates to a laminated circuit substrate configured by laminating a plurality of thermoplastic resin layers.
2. Description of the Related Art
International Publication No. 2010/113539 discloses a laminated circuit substrate to be mounted on a communication device such as a smart phone or a mobile phone.
The laminated circuit substrate disclosed in International Publication No. 2010/113539 has been manufactured as follows. First, with respect to a sheet having one side to which a metal film is attached, etching is performed to the metal film. This provides a conductor pattern of a capacitor and a conductor pattern of a coil. A sheet is made of thermoplastic resin. Next, a plurality of the sheets are laminated, heated, and pressure bonded from upper and lower directions of the lamination direction. In this manner, International Publication No. 2010/113539 discloses a laminated circuit substrate including therein a capacitor and a coil has been manufactured.
However, thermoplastic resin softens and flows due to heat and pressure at the time of thermocompression bonding. Therefore, when the laminated circuit substrate disclosed in International Publication No. 2010/113539 is thermocompression bonded, thermoplastic resin between conductor patterns that define a capacitor or a coil may possibly flow in large quantity to the outside of a portion between the conductor patterns, and a distance between the conductor patterns that face each other across thermoplastic resin layers may possibly be changed.
In a case of a capacitor, for example, as the distance between conductor patterns that define the capacitor is changed, the capacitance between the conductor patterns is changed. In addition, in a case of a coil, as the distance between conductor patterns that define the coil is changed, the line capacitance between the conductor patterns is changed. Therefore, when a temperature or pressure affecting the conductor patterns is changed at the time of thermocompression bonding, such element values (capacitance and inductance) are easily changed.
Accordingly, the laminated circuit substrate disclosed in International Publication No. 2010/113539 manufactured by laminating thermoplastic resin layers and thermocompression bonding the layers has a problem that it is hard to provide a capacitor or a coil having a highly accurate element value of which the individual difference is small.